The gospel on celebrity and pop culture

Los Angeles' Museum of Contemporary Art marked its 31st year Saturday with celebrities and art powerhouses alike, following up last year's powerful, Brangelina- and Lady Gaga-blessed 30th birthday with gusto.

Conceived by artist Doug Aitken, the Artist's Museum Happening shut down Grand Avenue in downtown L.A. for what Aitken fancied a "culture collision," with live art installations and musical performances from the likes of Beck.

Gwen Stefani and Gavin Rossdale made it date night, both clad in black and circulating with MOCA honcho Eli Broad and a slew of Hollywood beauties including Mila Kunis, Kate Bosworth, Malin Ackerman, Rachel Bilson, Rose McGowan and Chloë Sevigny.

After the Grey Goose cocktail hour, the museum invited guests for dinner and an Aitken-curated musical set from Natalie Portman's ex, Devendra Banhart, the aforementioned Beck and international singer and political activist Caetano Veloso.

"It was very mellow," Kunis said, mingling outside the tented affair with a female friend. "I felt like I was at the Hollywood Bowl with a glass of wine. I just wish I weren't in 5-inch heels."

Architect Frank Gehry, whose Walt Disney Concert Hall was only a few dozen yards away from the shindig, attended with his wife, Berta. Also in for the celebration were Francesco Vezzoli, who choreographed the Gaga number from last year's gala, and MOCA mainstay supporter Dasha Zhukova.

After the number, Aitken surprised the crowd with an interpretation of a cattle auction (as if there weren't enough actors herded in for the affair), during which guests Patricia and Rosanna Arquette and comedian Will Ferrell and wife Viveca Paulin looked on as auctioneers raffled off conceptual cattle beneath a light installation.